Biological diversity is the sum of all species of microbial organisms, plants, and animals on the face of Earth. Azerbaijan possesses the richest natural reserves among all other Caucasian countries. The nine biomes of Azerbaijan are home to some 4500 species of multicellular plants, accounting for 64% of the plant kingdom of the whole Caucasian region and 24% of that of the former Soviet Union. 168 species of plants out of 600 belong exclusively to the flora of Azerbaijan, while 432 — to the Caucasian flora.

140 rare and endangered species are included in the Red Book of Azerbaijan.

18 thousand species of animals are registered in Azerbaijan. The contemporary fauna of Azerbaijan includes 97 species of mammals, 357 species of birds, nearly 100 species of fish, 67 species and subspecies of reptiles and amphibians, and nearly 15 thousand species of insects.

The Red Book of Azerbaijan includes 14 mammal species (gazelle, leopard, bezoar goat, mountain sheep, etc), 36 bird species (partridge, bustard, shrike, little bustard, spoon-bill, etc), 13 species of amphibians and reptiles (triton, Syrian garlic frog, Esculapus snake), 5 fish species ( eel, trout, Zosterops, etc) and 40 insect species and subspecies (Talysh eodorcadion, Apollo, Talysh Brahmaea, etc.). Such a diversity of biological species is due to the country's geological history and various climate conditions.

Environmental protection, exploration of nature, and creation of preserves play an important role in the preservation of the country's ecosystem. Rare and endangered species of animals and plants are protected in specially designed areas.